From dd578cb290d89a810b95098cec113dee7345737a Mon Sep 17 00:00:00 2001
From: Kris Nuttycombe <kris@nutty.land>
Date: Thu, 24 Mar 2022 17:02:43 -0600
Subject: [PATCH] Restore legacy default Sapling addresses to the keystore.

Prior to zcash/zcash@90e59c3be0d15152b3d0da5bb069930846c2877b Sapling
default payment addresses were added to the in-memory keystore whenever
a full viewing key was added, or loaded from disk. After that change,
the Sapling address was no longer being restored to the in-memory
keystore on wallet load; instead, z_getnewaddress and
z_getnewaddressforaccount both persist the address to the keystore
directly. This commit adds handling to `LoadCaches` to correctly persist
the default address to the wallet database, and add it to the in-memory
keystore, when this condition is detected.
---
 src/wallet/wallet.cpp | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 4697a90d6..197e50d9b 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -1136,6 +1136,32 @@ bool CWallet::LoadCaches()
         }
     }
 
+    // Sapling legacy addresses were not directly added to the keystore; instead,
+    // the default address for each key was automatically added to the in-memory
+    // keystore, but not persisted. Following the addition of unified addresses,
+    // all addresses must be written to the wallet database explicitly.
+    auto legacySeed = GetLegacyHDSeed();
+    if (legacySeed.has_value()) {
+        for (const auto& [saplingIvk, keyMeta] : mapSaplingZKeyMetadata) {
+            // This condition only applies for keys derived from the legacy seed
+            if (keyMeta.seedFp == legacySeed.value().Fingerprint()) {
+                SaplingExtendedFullViewingKey extfvk;
+                if (GetSaplingFullViewingKey(saplingIvk, extfvk)) {
+                    auto defaultAddress = extfvk.DefaultAddress();
+                    if (!HaveSaplingIncomingViewingKey(defaultAddress)) {
+                        // restore the address to the keystore and persist it so that
+                        // the database state is consistent.
+                        if (!AddSaplingPaymentAddress(saplingIvk, defaultAddress)) {
+                            LogPrintf("%s: Error: Failed to write legacy Sapling payment address to the wallet database.\n",
+                                __func__);
+                            return false;
+                        }
+                    }
+                }
+            }
+        }
+    }
+
     // Restore decrypted Orchard notes.
     for (const auto& [_, walletTx] : mapWallet) {
         if (!walletTx.orchardTxMeta.empty()) {